coders/histogram.c - platform/external/ImageMagick - Gitiles

 /*
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %                                                                             %
 %                                                                             %
 %                                                                             %
 %       H   H  IIIII  SSSSS  TTTTT   OOO    GGGG  RRRR    AAA   M   M         %
 %       H   H    I    SS       T    O   O  G      R   R  A   A  MM MM         %
 %       HHHHH    I     SSS     T    O   O  G  GG  RRRR   AAAAA  M M M         %
 %       H   H    I       SS    T    O   O  G   G  R R    A   A  M   M         %
 %       H   H  IIIII  SSSSS    T     OOO    GGG   R  R   A   A  M   M         %
 %                                                                             %
 %                                                                             %
 %                          Write A Histogram Image.                           %
 %                                                                             %
 %                              Software Design                                %
 %                                John Cristy                                  %
 %                                 July 1992                                   %
 %                                                                             %
 %                                                                             %
 %  Copyright 1999-2011 ImageMagick Studio LLC, a non-profit organization      %
 %  dedicated to making software imaging solutions freely available.           %
 %                                                                             %
 %  You may not use this file except in compliance with the License.  You may  %
 %  obtain a copy of the License at                                            %
 %                                                                             %
 %    http://www.imagemagick.org/script/license.php                            %
 %                                                                             %
 %  Unless required by applicable law or agreed to in writing, software        %
 %  distributed under the License is distributed on an "AS IS" BASIS,          %
 %  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.   %
 %  See the License for the specific language governing permissions and        %
 %  limitations under the License.                                             %
 %                                                                             %
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %
 %
 */

 /*
   Include declarations.
 */
 #include "MagickCore/studio.h"
 #include "MagickCore/property.h"
 #include "MagickCore/blob.h"
 #include "MagickCore/blob-private.h"
 #include "MagickCore/cache.h"
 #include "MagickCore/color.h"
 #include "MagickCore/color-private.h"
 #include "MagickCore/constitute.h"
 #include "MagickCore/exception.h"
 #include "MagickCore/exception-private.h"
 #include "MagickCore/geometry.h"
 #include "MagickCore/histogram.h"
 #include "MagickCore/image-private.h"
 #include "MagickCore/magick.h"
 #include "MagickCore/memory_.h"
 #include "MagickCore/monitor.h"
 #include "MagickCore/monitor-private.h"
 #include "MagickCore/option.h"
 #include "MagickCore/pixel-accessor.h"
 #include "MagickCore/quantum-private.h"
 #include "MagickCore/resource_.h"
 #include "MagickCore/static.h"
 #include "MagickCore/statistic.h"
 #include "MagickCore/string_.h"
 #include "MagickCore/module.h"
 #include "MagickCore/utility.h"

 /*
   Forward declarations.
 */
 static MagickBooleanType
   WriteHISTOGRAMImage(const ImageInfo *,Image *,ExceptionInfo *);

 /*
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %                                                                             %
 %                                                                             %
 %                                                                             %
 %   R e g i s t e r H I S T O G R A M I m a g e                               %
 %                                                                             %
 %                                                                             %
 %                                                                             %
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %
 %  RegisterHISTOGRAMImage() adds attributes for the Histogram image format
 %  to the list of supported formats.  The attributes include the image format
 %  tag, a method to read and/or write the format, whether the format
 %  supports the saving of more than one frame to the same file or blob,
 %  whether the format supports native in-memory I/O, and a brief
 %  description of the format.
 %
 %  The format of the RegisterHISTOGRAMImage method is:
 %
 %      size_t RegisterHISTOGRAMImage(void)
 %
 */
 ModuleExport size_t RegisterHISTOGRAMImage(void)
 {
   MagickInfo
     *entry;

   entry=SetMagickInfo("HISTOGRAM");
   entry->encoder=(EncodeImageHandler *) WriteHISTOGRAMImage;
   entry->adjoin=MagickFalse;
   entry->format_type=ImplicitFormatType;
   entry->description=ConstantString("Histogram of the image");
   entry->module=ConstantString("HISTOGRAM");
   (void) RegisterMagickInfo(entry);
   return(MagickImageCoderSignature);
 }

 /*
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %                                                                             %
 %                                                                             %
 %                                                                             %
 %   U n r e g i s t e r H I S T O G R A M I m a g e                           %
 %                                                                             %
 %                                                                             %
 %                                                                             %
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %
 %  UnregisterHISTOGRAMImage() removes format registrations made by the
 %  HISTOGRAM module from the list of supported formats.
 %
 %  The format of the UnregisterHISTOGRAMImage method is:
 %
 %      UnregisterHISTOGRAMImage(void)
 %
 */
 ModuleExport void UnregisterHISTOGRAMImage(void)
 {
   (void) UnregisterMagickInfo("HISTOGRAM");
 }

 /*
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %                                                                             %
 %                                                                             %
 %                                                                             %
 %   W r i t e H I S T O G R A M I m a g e                                     %
 %                                                                             %
 %                                                                             %
 %                                                                             %
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %
 %  WriteHISTOGRAMImage() writes an image to a file in Histogram format.
 %  The image shows a histogram of the color (or gray) values in the image.  The
 %  image consists of three overlaid histograms:  a red one for the red channel,
 %  a green one for the green channel, and a blue one for the blue channel.  The
 %  image comment contains a list of unique pixel values and the number of times
 %  each occurs in the image.
 %
 %  This method is strongly based on a similar one written by
 %  muquit@warm.semcor.com which in turn is based on ppmhistmap of netpbm.
 %
 %  The format of the WriteHISTOGRAMImage method is:
 %
 %      MagickBooleanType WriteHISTOGRAMImage(const ImageInfo *image_info,
 %        Image *image,ExceptionInfo *exception)
 %
 %  A description of each parameter follows.
 %
 %    o image_info: the image info.
 %
 %    o image:  The image.
 %
 %    o exception: return any errors or warnings in this structure.
 %
 */

 static inline size_t MagickMax(const size_t x,const size_t y)
 {
   if (x > y)
     return(x);
   return(y);
 }

 static MagickBooleanType WriteHISTOGRAMImage(const ImageInfo *image_info,
   Image *image,ExceptionInfo *exception)
 {
 #define HistogramDensity  "256x200"

   char
     filename[MaxTextExtent];

   const char
     *option;

   Image
     *histogram_image;

   ImageInfo
     *write_info;

   MagickBooleanType
     status;

   PixelInfo
     *histogram;

   MagickRealType
     maximum,
     scale;

   RectangleInfo
     geometry;

   register const Quantum
     *p;

   register Quantum
     *q,
     *r;

   register ssize_t
     x;

   size_t
     length;

   ssize_t
     y;

   /*
     Allocate histogram image.
   */
   assert(image_info != (const ImageInfo *) NULL);
   assert(image_info->signature == MagickSignature);
   assert(image != (Image *) NULL);
   assert(image->signature == MagickSignature);
   if (image->debug != MagickFalse)
     (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",
       image_info->filename);
   SetGeometry(image,&geometry);
   if (image_info->density == (char *) NULL)
     (void) ParseAbsoluteGeometry(HistogramDensity,&geometry);
   else
     (void) ParseAbsoluteGeometry(image_info->density,&geometry);
   histogram_image=CloneImage(image,geometry.width,geometry.height,MagickTrue,
     exception);
   if (histogram_image == (Image *) NULL)
     ThrowWriterException(ResourceLimitError,"MemoryAllocationFailed");
   (void) SetImageStorageClass(histogram_image,DirectClass,exception);
   /*
     Allocate histogram count arrays.
   */
   length=MagickMax((size_t) ScaleQuantumToChar((Quantum) QuantumRange)+1UL,
     histogram_image->columns);
   histogram=(PixelInfo *) AcquireQuantumMemory(length,
     sizeof(*histogram));
   if (histogram == (PixelInfo *) NULL)
     {
       histogram_image=DestroyImage(histogram_image);
       ThrowWriterException(ResourceLimitError,"MemoryAllocationFailed");
     }
   /*
     Initialize histogram count arrays.
   */
   (void) ResetMagickMemory(histogram,0,length*sizeof(*histogram));
   for (y=0; y < (ssize_t) image->rows; y++)
   {
     p=GetVirtualPixels(image,0,y,image->columns,1,exception);
     if (p == (const Quantum *) NULL)
       break;
     for (x=0; x < (ssize_t) image->columns; x++)
     {
       if ((GetPixelRedTraits(image) & UpdatePixelTrait) != 0)
         histogram[ScaleQuantumToChar(GetPixelRed(image,p))].red++;
       if ((GetPixelGreenTraits(image) & UpdatePixelTrait) != 0)
         histogram[ScaleQuantumToChar(GetPixelGreen(image,p))].green++;
       if ((GetPixelBlueTraits(image) & UpdatePixelTrait) != 0)
         histogram[ScaleQuantumToChar(GetPixelBlue(image,p))].blue++;
       p+=GetPixelChannels(image);
     }
   }
   maximum=histogram[0].red;
   for (x=0; x < (ssize_t) histogram_image->columns; x++)
   {
     if (((GetPixelRedTraits(image) & UpdatePixelTrait) != 0) &&
         (maximum < histogram[x].red))
       maximum=histogram[x].red;
     if (((GetPixelGreenTraits(image) & UpdatePixelTrait) != 0) &&
         (maximum < histogram[x].green))
       maximum=histogram[x].green;
     if (((GetPixelBlueTraits(image) & UpdatePixelTrait) != 0) &&
         (maximum < histogram[x].blue))
       maximum=histogram[x].blue;
   }
   scale=(MagickRealType) histogram_image->rows/maximum;
   /*
     Initialize histogram image.
   */
   (void) QueryColorCompliance("#000000",AllCompliance,
     &histogram_image->background_color,exception);
   (void) SetImageBackgroundColor(histogram_image);
   for (x=0; x < (ssize_t) histogram_image->columns; x++)
   {
     q=GetAuthenticPixels(histogram_image,x,0,1,histogram_image->rows,exception);
     if (q == (Quantum *) NULL)
       break;
     if ((GetPixelRedTraits(image) & UpdatePixelTrait) != 0)
       {
         y=(ssize_t) ceil(histogram_image->rows-scale*histogram[x].red-0.5);
         r=q+y;
         for ( ; y < (ssize_t) histogram_image->rows; y++)
         {
           SetPixelRed(histogram_image,QuantumRange,r);
           r++;
         }
       }
     if ((GetPixelGreenTraits(image) & UpdatePixelTrait) != 0)
       {
         y=(ssize_t) ceil(histogram_image->rows-scale*histogram[x].green-0.5);
         r=q+y;
         for ( ; y < (ssize_t) histogram_image->rows; y++)
         {
           SetPixelGreen(histogram_image,QuantumRange,r);
           r++;
         }
       }
     if ((GetPixelBlueTraits(image) & UpdatePixelTrait) != 0)
       {
         y=(ssize_t) ceil(histogram_image->rows-scale*histogram[x].blue-0.5);
         r=q+y;
         for ( ; y < (ssize_t) histogram_image->rows; y++)
         {
           SetPixelBlue(histogram_image,QuantumRange,r);
           r++;
         }
       }
     if (SyncAuthenticPixels(histogram_image,exception) == MagickFalse)
       break;
     status=SetImageProgress(image,SaveImageTag,y,histogram_image->rows);
     if (status == MagickFalse)
       break;
   }
   /*
     Relinquish resources.
   */
   histogram=(PixelInfo *) RelinquishMagickMemory(histogram);
   option=GetImageOption(image_info,"histogram:unique-colors");
   if ((option == (const char *) NULL) || (IsMagickTrue(option) != MagickFalse))
     {
       FILE
         *file;

       int
         unique_file;

       /*
         Add a unique colors as an image comment.
       */
       file=(FILE *) NULL;
       unique_file=AcquireUniqueFileResource(filename);
       if (unique_file != -1)
         file=fdopen(unique_file,"wb");
       if ((unique_file != -1) && (file != (FILE *) NULL))
         {
           char
             *property;

           (void) GetNumberColors(image,file,exception);
           (void) fclose(file);
           property=FileToString(filename,~0UL,exception);
           if (property != (char *) NULL)
             {
               (void) SetImageProperty(histogram_image,"comment",property,
                 exception);
               property=DestroyString(property);
             }
         }
       (void) RelinquishUniqueFileResource(filename);
     }
   /*
     Write Histogram image.
   */
   (void) CopyMagickString(histogram_image->filename,image_info->filename,
     MaxTextExtent);
   write_info=CloneImageInfo(image_info);
   (void) SetImageInfo(write_info,1,exception);
   if (LocaleCompare(write_info->magick,"HISTOGRAM") == 0)
     (void) FormatLocaleString(histogram_image->filename,MaxTextExtent,
       "miff:%s",write_info->filename);
   status=WriteImage(write_info,histogram_image,exception);
   histogram_image=DestroyImage(histogram_image);
   write_info=DestroyImageInfo(write_info);
   return(status);
 }
	/*
	%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
	% %
	% %
	% %
	% H H IIIII SSSSS TTTTT OOO GGGG RRRR AAA M M %
	% H H I SS T O O G R R A A MM MM %
	% HHHHH I SSS T O O G GG RRRR AAAAA M M M %
	% H H I SS T O O G G R R A A M M %
	% H H IIIII SSSSS T OOO GGG R R A A M M %
	% %
	% %
	% Write A Histogram Image. %
	% %
	% Software Design %
	% John Cristy %
	% July 1992 %
	% %
	% %
	% Copyright 1999-2011 ImageMagick Studio LLC, a non-profit organization %
	% dedicated to making software imaging solutions freely available. %
	% %
	% You may not use this file except in compliance with the License. You may %
	% obtain a copy of the License at %
	% %
	% http://www.imagemagick.org/script/license.php %
	% %
	% Unless required by applicable law or agreed to in writing, software %
	% distributed under the License is distributed on an "AS IS" BASIS, %
	% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. %
	% See the License for the specific language governing permissions and %
	% limitations under the License. %
	% %
	%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
	%
	%
	*/

	/*
	Include declarations.
	*/
	#include "MagickCore/studio.h"
	#include "MagickCore/property.h"
	#include "MagickCore/blob.h"
	#include "MagickCore/blob-private.h"
	#include "MagickCore/cache.h"
	#include "MagickCore/color.h"
	#include "MagickCore/color-private.h"
	#include "MagickCore/constitute.h"
	#include "MagickCore/exception.h"
	#include "MagickCore/exception-private.h"
	#include "MagickCore/geometry.h"
	#include "MagickCore/histogram.h"
	#include "MagickCore/image-private.h"
	#include "MagickCore/magick.h"
	#include "MagickCore/memory_.h"
	#include "MagickCore/monitor.h"
	#include "MagickCore/monitor-private.h"
	#include "MagickCore/option.h"
	#include "MagickCore/pixel-accessor.h"
	#include "MagickCore/quantum-private.h"
	#include "MagickCore/resource_.h"
	#include "MagickCore/static.h"
	#include "MagickCore/statistic.h"
	#include "MagickCore/string_.h"
	#include "MagickCore/module.h"
	#include "MagickCore/utility.h"

	/*
	Forward declarations.
	*/
	static MagickBooleanType
	WriteHISTOGRAMImage(const ImageInfo ,Image ,ExceptionInfo *);

	/*
	%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
	% %
	% %
	% %
	% R e g i s t e r H I S T O G R A M I m a g e %
	% %
	% %
	% %
	%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
	%
	% RegisterHISTOGRAMImage() adds attributes for the Histogram image format
	% to the list of supported formats. The attributes include the image format
	% tag, a method to read and/or write the format, whether the format
	% supports the saving of more than one frame to the same file or blob,
	% whether the format supports native in-memory I/O, and a brief
	% description of the format.
	%
	% The format of the RegisterHISTOGRAMImage method is:
	%
	% size_t RegisterHISTOGRAMImage(void)
	%
	*/
	ModuleExport size_t RegisterHISTOGRAMImage(void)
	{
	MagickInfo
	*entry;

	entry=SetMagickInfo("HISTOGRAM");
	entry->encoder=(EncodeImageHandler *) WriteHISTOGRAMImage;
	entry->adjoin=MagickFalse;
	entry->format_type=ImplicitFormatType;
	entry->description=ConstantString("Histogram of the image");
	entry->module=ConstantString("HISTOGRAM");
	(void) RegisterMagickInfo(entry);
	return(MagickImageCoderSignature);
	}

	/*
	%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
	% %
	% %
	% %
	% U n r e g i s t e r H I S T O G R A M I m a g e %
	% %
	% %
	% %
	%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
	%
	% UnregisterHISTOGRAMImage() removes format registrations made by the
	% HISTOGRAM module from the list of supported formats.
	%
	% The format of the UnregisterHISTOGRAMImage method is:
	%
	% UnregisterHISTOGRAMImage(void)
	%
	*/
	ModuleExport void UnregisterHISTOGRAMImage(void)
	{
	(void) UnregisterMagickInfo("HISTOGRAM");
	}

	/*
	%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
	% %
	% %
	% %
	% W r i t e H I S T O G R A M I m a g e %
	% %
	% %
	% %
	%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
	%
	% WriteHISTOGRAMImage() writes an image to a file in Histogram format.
	% The image shows a histogram of the color (or gray) values in the image. The
	% image consists of three overlaid histograms: a red one for the red channel,
	% a green one for the green channel, and a blue one for the blue channel. The
	% image comment contains a list of unique pixel values and the number of times
	% each occurs in the image.
	%
	% This method is strongly based on a similar one written by
	% muquit@warm.semcor.com which in turn is based on ppmhistmap of netpbm.
	%
	% The format of the WriteHISTOGRAMImage method is:
	%
	% MagickBooleanType WriteHISTOGRAMImage(const ImageInfo *image_info,
	% Image image,ExceptionInfo exception)
	%
	% A description of each parameter follows.
	%
	% o image_info: the image info.
	%
	% o image: The image.
	%
	% o exception: return any errors or warnings in this structure.
	%
	*/

	static inline size_t MagickMax(const size_t x,const size_t y)
	{
	if (x > y)
	return(x);
	return(y);
	}

	static MagickBooleanType WriteHISTOGRAMImage(const ImageInfo *image_info,
	Image image,ExceptionInfo exception)
	{
	#define HistogramDensity "256x200"

	char
	filename[MaxTextExtent];

	const char
	*option;

	Image
	*histogram_image;

	ImageInfo
	*write_info;

	MagickBooleanType
	status;

	PixelInfo
	*histogram;

	MagickRealType
	maximum,
	scale;

	RectangleInfo
	geometry;

	register const Quantum
	*p;

	register Quantum
	*q,
	*r;

	register ssize_t
	x;

	size_t
	length;

	ssize_t
	y;

	/*
	Allocate histogram image.
	*/
	assert(image_info != (const ImageInfo *) NULL);
	assert(image_info->signature == MagickSignature);
	assert(image != (Image *) NULL);
	assert(image->signature == MagickSignature);
	if (image->debug != MagickFalse)
	(void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",
	image_info->filename);
	SetGeometry(image,&geometry);
	if (image_info->density == (char *) NULL)
	(void) ParseAbsoluteGeometry(HistogramDensity,&geometry);
	else
	(void) ParseAbsoluteGeometry(image_info->density,&geometry);
	histogram_image=CloneImage(image,geometry.width,geometry.height,MagickTrue,
	exception);
	if (histogram_image == (Image *) NULL)
	ThrowWriterException(ResourceLimitError,"MemoryAllocationFailed");
	(void) SetImageStorageClass(histogram_image,DirectClass,exception);
	/*
	Allocate histogram count arrays.
	*/
	length=MagickMax((size_t) ScaleQuantumToChar((Quantum) QuantumRange)+1UL,
	histogram_image->columns);
	histogram=(PixelInfo *) AcquireQuantumMemory(length,
	sizeof(*histogram));
	if (histogram == (PixelInfo *) NULL)
	{
	histogram_image=DestroyImage(histogram_image);
	ThrowWriterException(ResourceLimitError,"MemoryAllocationFailed");
	}
	/*
	Initialize histogram count arrays.
	*/
	(void) ResetMagickMemory(histogram,0,lengthsizeof(histogram));
	for (y=0; y < (ssize_t) image->rows; y++)
	{
	p=GetVirtualPixels(image,0,y,image->columns,1,exception);
	if (p == (const Quantum *) NULL)
	break;
	for (x=0; x < (ssize_t) image->columns; x++)
	{
	if ((GetPixelRedTraits(image) & UpdatePixelTrait) != 0)
	histogram[ScaleQuantumToChar(GetPixelRed(image,p))].red++;
	if ((GetPixelGreenTraits(image) & UpdatePixelTrait) != 0)
	histogram[ScaleQuantumToChar(GetPixelGreen(image,p))].green++;
	if ((GetPixelBlueTraits(image) & UpdatePixelTrait) != 0)
	histogram[ScaleQuantumToChar(GetPixelBlue(image,p))].blue++;
	p+=GetPixelChannels(image);
	}
	}
	maximum=histogram[0].red;
	for (x=0; x < (ssize_t) histogram_image->columns; x++)
	{
	if (((GetPixelRedTraits(image) & UpdatePixelTrait) != 0) &&
	(maximum < histogram[x].red))
	maximum=histogram[x].red;
	if (((GetPixelGreenTraits(image) & UpdatePixelTrait) != 0) &&
	(maximum < histogram[x].green))
	maximum=histogram[x].green;
	if (((GetPixelBlueTraits(image) & UpdatePixelTrait) != 0) &&
	(maximum < histogram[x].blue))
	maximum=histogram[x].blue;
	}
	scale=(MagickRealType) histogram_image->rows/maximum;
	/*
	Initialize histogram image.
	*/
	(void) QueryColorCompliance("#000000",AllCompliance,
	&histogram_image->background_color,exception);
	(void) SetImageBackgroundColor(histogram_image);
	for (x=0; x < (ssize_t) histogram_image->columns; x++)
	{
	q=GetAuthenticPixels(histogram_image,x,0,1,histogram_image->rows,exception);
	if (q == (Quantum *) NULL)
	break;
	if ((GetPixelRedTraits(image) & UpdatePixelTrait) != 0)
	{
	y=(ssize_t) ceil(histogram_image->rows-scale*histogram[x].red-0.5);
	r=q+y;
	for ( ; y < (ssize_t) histogram_image->rows; y++)
	{
	SetPixelRed(histogram_image,QuantumRange,r);
	r++;
	}
	}
	if ((GetPixelGreenTraits(image) & UpdatePixelTrait) != 0)
	{
	y=(ssize_t) ceil(histogram_image->rows-scale*histogram[x].green-0.5);
	r=q+y;
	for ( ; y < (ssize_t) histogram_image->rows; y++)
	{
	SetPixelGreen(histogram_image,QuantumRange,r);
	r++;
	}
	}
	if ((GetPixelBlueTraits(image) & UpdatePixelTrait) != 0)
	{
	y=(ssize_t) ceil(histogram_image->rows-scale*histogram[x].blue-0.5);
	r=q+y;
	for ( ; y < (ssize_t) histogram_image->rows; y++)
	{
	SetPixelBlue(histogram_image,QuantumRange,r);
	r++;
	}
	}
	if (SyncAuthenticPixels(histogram_image,exception) == MagickFalse)
	break;
	status=SetImageProgress(image,SaveImageTag,y,histogram_image->rows);
	if (status == MagickFalse)
	break;
	}
	/*
	Relinquish resources.
	*/
	histogram=(PixelInfo *) RelinquishMagickMemory(histogram);
	option=GetImageOption(image_info,"histogram:unique-colors");
	if ((option == (const char *) NULL) \|\| (IsMagickTrue(option) != MagickFalse))
	{
	FILE
	*file;

	int
	unique_file;

	/*
	Add a unique colors as an image comment.
	*/
	file=(FILE *) NULL;
	unique_file=AcquireUniqueFileResource(filename);
	if (unique_file != -1)
	file=fdopen(unique_file,"wb");
	if ((unique_file != -1) && (file != (FILE *) NULL))
	{
	char
	*property;

	(void) GetNumberColors(image,file,exception);
	(void) fclose(file);
	property=FileToString(filename,~0UL,exception);
	if (property != (char *) NULL)
	{
	(void) SetImageProperty(histogram_image,"comment",property,
	exception);
	property=DestroyString(property);
	}
	}
	(void) RelinquishUniqueFileResource(filename);
	}
	/*
	Write Histogram image.
	*/
	(void) CopyMagickString(histogram_image->filename,image_info->filename,
	MaxTextExtent);
	write_info=CloneImageInfo(image_info);
	(void) SetImageInfo(write_info,1,exception);
	if (LocaleCompare(write_info->magick,"HISTOGRAM") == 0)
	(void) FormatLocaleString(histogram_image->filename,MaxTextExtent,
	"miff:%s",write_info->filename);
	status=WriteImage(write_info,histogram_image,exception);
	histogram_image=DestroyImage(histogram_image);
	write_info=DestroyImageInfo(write_info);
	return(status);
	}